Transgenic technologies are prohibitively expensive for individual laboratories and require extremely skilled[unreadable] and dedicated personnel and institutional support. This is because first, many factors greatly affect[unreadable] expression levels of randomly inserted DNA, which leads to transgenes being transcriptionally silent at many[unreadable] chromosomal locations. In addition, there is a considerable risk as to whether targeted ES cells will[unreadable] contribute to the germline. As a result, no transgenic facility will guarantee transgene expression, nor that[unreadable] targeted ES cells will go to germline. Secondly, many investigators whose studies require the use of[unreadable] transgenic animals are not trained in their generation. This is partly the case for this program project where[unreadable] the expertise of investigators and their lab personnel range from extensive experience to very little[unreadable] experience. Therefore, the expertise that is available in the transgenic core at UMKC has also been[unreadable] included in this program project. The Director and Co-Director will assist the principal investigators in the[unreadable] design of constructs, educate personnel and students, and oversee the general operation of the core. The[unreadable] services of this core will not only be to generate transgenic mice, but to cross breed mice to generate the[unreadable] correct genotype, and to maintain the mice until ready for the Mechanical Strain Core or to be sent to the[unreadable] investigator. The purpose of this core is to provide efficient and economical service to the members of the[unreadable] Program Project plus the needed educational component. The core will also provide the following: 1)[unreadable] generation of transgenic embryos for screening of expression of Dmp1 and Mepe promoter fragments for[unreadable] osteocyte selectivity and response to mechanical load; 2) generation of transgenic mice expressing the 8[unreadable] and/or 10 kb Dmp1-Cre, intact MEPE or MEPE promoter fragments, 3). generation of wild type Cx43 and[unreadable] truncated Cx43 mice and their targeted expression in osteocytes; 4) generation of Dmp1-loxP and E-11-loxP[unreadable] mice; 5) generation of floxed mice lacking Dmp1 or E11 in osteocytes using various promoters regulating[unreadable] Cre expression; and 6) maintainance of all Cre mice needed for this project, including osteocalcin-Cre, 8[unreadable] (and/or 10) kb Dmp1 Cre, and 3.2 kb Col 1a1 ERt2-Cre mice. In addition, the Core will serve as a resource[unreadable] for consultation and training for prinicipal investigators, their students and personnel for genotyping and[unreadable] screening of transgenic and knockout mice.